KMU Past Paper Practice

Question:

A 62-year-old patient receives a drug that is extensively metabolized by the liver. Its inactive metabolites are subsequently removed in urine. Which statement most accurately describes the fate of the parent drug?

Options:

Correct Answer: Metabolism contributes to its overall elimination

Explanation: Elimination includes irreversible loss of active drug through metabolism as well as excretion; urinary removal of metabolites is only one part of the overall process.

Question:

A drug is cleared by both the liver and kidneys. The renal clearance is 6 L/hour and hepatic clearance is 9 L/hour, with other routes contributing negligibly. What is the approximate total body clearance?

Options:

Correct Answer: 15 L/hour

Explanation: Total body clearance is the sum of clearances contributed by eliminating organs; therefore 6 + 9 = 15 L/hour.

Question:

A pharmacologist compares two drugs eliminated at the same rate of 40 mg/hour. Drug P has a plasma concentration of 10 mg/L, while Drug Q has a concentration of 5 mg/L. Which interpretation is correct?

Options:

Correct Answer: Drug Q has twice the clearance of Drug P

Explanation: Clearance equals elimination rate divided by concentration. Drug P = 4 L/hour and Drug Q = 8 L/hour, so Q has twice the clearance.

Question:

A mother receiving medication is advised that a small amount of the drug may reach her breast-fed infant even though this route contributes little to total drug removal. How should breast milk be classified in this context?

Options:

Correct Answer: A minor excretory route

Explanation: Breast milk is quantitatively a minor route of drug excretion, but it can be clinically relevant because the nursing infant may be exposed.

Question:

A drug is secreted into bile and enters the intestinal lumen before leaving the body in feces. Which route best accounts for this drug loss?

Options:

Correct Answer: Biliary-fecal excretion

Explanation: Drug entering bile passes into the intestine and may ultimately leave in feces, representing the biliary-fecal route of excretion.

Question:

Two patients require the same target concentration of a drug and receive it at the same dosing interval. Patient X has a drug clearance of 3 L/hour and Patient Y has a clearance of 6 L/hour. Bioavailability is identical. Which dosage relationship is expected?

Options:

Correct Answer: Patient Y requires twice the maintenance dose

Explanation: Maintenance dose is directly proportional to clearance when target concentration, interval and bioavailability remain unchanged.

Question:

A drug is changed from intravenous administration to an oral preparation with bioavailability of 50%. The desired concentration, clearance and dosing interval remain unchanged. How should the maintenance dose be adjusted?

Options:

Correct Answer: Increase it approximately twofold

Explanation: Maintenance dose is divided by bioavailability. When F falls from 1 to 0.5, approximately twice the oral dose is required for the same systemic input.

Question:

Two children of the same age have markedly different body weights. The physician is asked to choose among the traditional pediatric formulae in the supplied pharmacology material. Which formula directly incorporates this difference?

Options:

Correct Answer: Clark’s formula

Explanation: Clark’s formula is based on body weight in pounds, whereas Young’s and Dilling’s formulae use the child’s age.

Question:

A 5-year-old child requires a medicine with an adult dose of 340 mg. Using Young’s formula, what dose is obtained?

Options:

Correct Answer: 100 mg

Explanation: Young’s formula gives 5/(5 + 12) × 340 = 5/17 × 340 = 100 mg.

Question:

A 12-year-old child is prescribed a medicine whose usual adult dose is 500 mg. If Dilling’s formula is used, which dose should be calculated?

Options:

Correct Answer: 300 mg

Explanation: Dilling’s formula is age/20 × adult dose; therefore 12/20 × 500 = 300 mg.

Question:

A child weighs 60 lb and requires a medicine with a standard adult dose of 500 mg. What dose is obtained using Clark’s formula?

Options:

Correct Answer: 200 mg

Explanation: Clark’s formula gives 60/150 × 500 = 200 mg.

Question:

Drug A and Drug B have identical clearance. Drug A distributes extensively into tissues and therefore has a much larger volume of distribution than Drug B. Which pharmacokinetic behavior is expected for Drug A?

Options:

Correct Answer: A longer plasma half-life

Explanation: Half-life is directly proportional to volume of distribution when clearance is unchanged; greater tissue distribution therefore prolongs half-life.

Question:

A patient receives a drug with a half-life of 6 hours. Treatment is stopped after several days of regular dosing. Assuming first-order kinetics, approximately what fraction of the drug will remain 18 hours after the last dose?

Options:

Correct Answer: One eighth

Explanation: Eighteen hours equals three half-lives: 1 → 1/2 → 1/4 → 1/8, so approximately 12.5% remains.

Question:

Two drugs are compared during pharmacokinetic teaching. Adenosine disappears extremely rapidly after administration, whereas amiodarone may persist for a prolonged period. Which parameter most directly expresses this difference in persistence?

Options:

Correct Answer: Plasma half-life

Explanation: Plasma half-life describes how rapidly drug concentration falls by 50% and therefore provides a direct measure of drug persistence in the body.

Question:

A drug following first-order kinetics is administered repeatedly. After one half-life, its average concentration has reached 50% of the eventual plateau. Approximately what percentage will have been reached after two half-lives?

Options:

Correct Answer: 75%

Explanation: Half of the remaining difference from steady state is covered during each half-life: 50% after one and 75% after two.

Question:

Two drugs are given by continuous administration. Drug R has a half-life of 4 hours and Drug S has a half-life of 20 hours. Their dosing rates are adjusted to achieve appropriate target concentrations. Which drug will approach its plateau concentration sooner?

Options:

Correct Answer: Drug R because its half-life is shorter

Explanation: Time to approach steady state depends mainly on half-life; a drug with a shorter half-life reaches its plateau sooner.

Question:

A drug follows first-order elimination. When its plasma concentration is 20 mg/L, 10 mg is eliminated during a particular interval. At a concentration of 10 mg/L, what amount would be expected to be eliminated during an equivalent interval?

Options:

Correct Answer: 5 mg

Explanation: In first-order kinetics the same fraction is removed per unit time; halving concentration therefore halves the amount eliminated during that interval.

Question:

A patient has a high concentration of ethanol in the body. During successive equal time intervals, approximately the same quantity is removed despite the changing concentration. Which feature of the elimination system best accounts for this pattern?

Options:

Correct Answer: Saturation of eliminating capacity

Explanation: Zero-order behavior occurs when the elimination pathway is capacity limited, producing removal of an approximately constant amount per unit time.

Question:

A student plots plasma concentration against time for two drugs. Drug X shows a constant fractional decline, whereas Drug Y is being removed by a saturated pathway. Which statement regarding half-life is most appropriate?

Options:

Correct Answer: Drug X has a relatively constant half-life

Explanation: A relatively constant half-life characterizes first-order elimination; with zero-order capacity-limited elimination, half-life is not constant in the same way.

Question:

A patient is receiving repeated doses of a drug following first-order kinetics. After three half-lives, the plasma concentration has approached about 87.5% of its eventual steady-state value. What best explains why each additional half-life produces a progressively smaller absolute increase?

Options:

Correct Answer: Half of the remaining difference is covered each half-life

Explanation: During first-order accumulation, each half-life closes half of the remaining gap to steady state, producing the sequence 50%, 75%, 87.5%, and about 94%.